Field of the Invention
Embodiments of the present disclosure relate generally to systems and methods to facilitate the investigation, monitoring and/or measurement of brain processes in living laboratory animals such, for example, as rodents.
Description of the Related Art
The brain is the organ that is responsible for motor behavior, perception, cognition and the maintenance of many homeostatic functions. Malfunctions of the brain may be the cause of a variety of neurological and psychiatric diseases and disorders. The function of the brain resides both in the structural connectivity of its network of cells and in the dynamic interactions between these nerve cells. Just as certain cardiovascular diagnostics are best performed on an active heart being challenged by physical exercise, monitoring and measuring techniques for assessing the function and malfunction of brain processes are at their most effective while the brain is engaged in active stimulus processing and motor control. This requires an awake animal actively engaged in behavior.
Various arrangements have been proposed for eliciting activity by an animal under investigation so that one or more functions in the brain of the animal can be measured, assessed or otherwise monitored. Hölscher et al. disclose, in a 2005 paper published in the Journal of Experimental Biology [J. Exp. Biol; Vol. 208, Issue 3, at pp. 561-569], a suspended, spherical treadmill within which an animal is free to walk in different directions while its head is fixed to permit the recording of nerve cell electrical activity and/or other measurements. By moving its feet, the animal under investigation can move the substrate upon which it is supported in any direction or at any angle relative to a reference plane. Such motor behavior can be spontaneous or in response to sensory stimuli or signals, allowing for the experimental presentation of reinforcers. A motivated animal can learn to control the occurrence of reinforcers through decision making and behavioral actions while its brain processes are being monitored and measured.
In U.S. Pat. No. 8,485,133 entitled “Mobile Platform Arrangement” and issued to Osmekhin et al. on Jul. 16, 2013, there is proposed a variation on the Hölscher et al. concept. In the Osmekhin et al. arrangement, however, the movable substrate upon which an animal moves is not a spherical treadmill as proposed by Hölscher et al. Instead. Osmekhin et al. propose a flat-bottomed experimental cage which glides above an underlying air table support surface. Movement of the experimental cage can occur in any horizontal direction or orientation, up until the point at which the animal under investigation contacts the outside wall of the cage. The air table support surface of Osmekhin et al. has a nominal profile dimension (e.g., an outer table surface diameter) that is at least twice as large as the nominal profile dimension of the movable substrate floating above and along the air table support surface.
The inventor herein has recognized that a general disadvantage associated with arrangements of the aforementioned type is the amount of floor or table space which must be exclusively allocated and dedicated to their deployment and use. In many laboratory environments, the researcher(s) may need to reserve space for other equipment and instruments required for a particular set of experiments. A substantial amount of space is also typically required for such activities as animal preparation. In situations where space is limited, the use of conventional arrangements for eliciting animal activity suitable for brain function monitoring may be precluded entirely, necessitate a reduction in efficiency due to the remote placement of other equipment, or reduce the ability of a laboratory to accommodate concurrent investigative activity in related or different fields.